Many consumer products are applied to the skin or hair, and/or involve the sensory experience of touching. Consumer preferences are influenced by a multitude of factors, including product effectiveness, the feel of the product, fragrance, durability, ease of rinsing, etc. One way to determine consumer preferences is by conducting consumer marketing tests, in which a representative group of consumers, or panelists, provide feedback after using a product. Consumer marketing tests have several drawbacks, however. Because panelists must be appropriately selected and compensated for their time, such tests are expensive and time consuming. Human feedback is inherently subjective, and may raise concerns about reliability. Products must be safe for human testing, and the analyses that can be performed after application also are limited. There exists a need to reduce testing with panelists and broaden the range of product testing that can be performed, by providing a method of using an artificial substrate having properties of mammalian keratinous tissue to reproduce a range of properties most relevant to a given product.
Some product testing can be performed using model systems. Artificial substrates are available that, to some extent, imitate human skin. Alternatively, keratinous tissue from animals or human cadavers may be used. Whereas these and other available models may be suitable for some types of product testing, all have significant limitations. Cadaver tissue is costly, and neither cadaver nor animal tissue is able to truly mimic various types of living, human tissue.
While currently available artificial substrates provide better models to assess such characteristics, they also have many disadvantages. First, currently available substrates typically comprise more than one layer which may include coatings and textures to allow controlled variation of physical properties representative of keratinous tissue. Second, currently available artificial substrates are expensive, placing constraints on research and development. Third, many currently available artificial substrates require significant labor investment to prepare; those that don't are expensively priced. For example, test preparers must coat the substrate or wash or sterilize the substrates so that they may be reused. Fourth, currently available artificial substrates are generally nonporous and non-absorbent, so they do not truly mimic keratinous tissue responses. There is a desire for a less expensive substrate which is porous and absorbent and which does not require preparation or re-use.